That's why - with the players' backing - Fifa is carrying out blood tests for the very first time at the World Cup.
Earlier this week they made a video of their testing process, partly to educate and partly to show they've nothing to hide.
Just as they did at France 98, football's world governing body has chosen one game to illustrate how thorough their drug testing operation is - the match between USA and Portugal.
It is under scrutiny for two reasons; blood testing has been introduced for the first time at a World Cup.
And Fifa has been criticised for not allowing representatives from the World Anti-Doping Agency (Wada) - an independent body - to sit in and observe football's medical team at work.
Professor Jiri Dvorak is the chief medical officer for World Cup 2002 and conducts many of the tests himself.
He says he wouldn't have a problem if, in future, Fifa decided to let Wada in. What he questions is whether their presence is really necessary at all.
"We try to do professional work for Fifa and nothing is hidden," he said.
"We do not see any rational reason to have any independent observers. No-one observes me when I'm doing my medical work in my hospital, its a parallel situation."
But would Fifa consider showing Wada the video made of the testing procedure at this World Cup?
"The video from 98 we have supplied to the International Olympic Committee for their internal use, to learn, because we are colleagues.
"I will need the agreement of the players but, if I receive it, there is no problem releasing the 2002 video.
"We wish that everybody can see it and that is also acknowledged by Wada."
With more money than ever in football the temptation to win at all costs is always there, but does the punishment fit the crime?
"We estimate medically the severity of the violation of the regulation," said Jiri. "The Disciplinary Committee will decide on the sanction.
"Fifa is not willing to have a unique sanction for anything because there is definitely a discrepancy if you take anabolic steroids or if you take some other drug on the list, so it has to be individually dealt with."
Is 'I didn't know I was taking it' ever a defence, I asked him?
"We have issued a very strong warning in this respect because a number of food supplements sold over the counter are contaminated by non-declared nandrolone," he said.
"In a way this could be considered a kind of criminal act. But if a player can prove this particular supplement is contaminated then he has to go to the producer of that particular substance and discuss with him the consequences".